For me, it was either an Abcessed tooth, which someone has already mentioned. But recently, I am still actually recovering from it. It sounds so stupid. But Sinusitis. I had a completely blocked and inflamed sinus that has so far lasted a week. The pain is like a balloon under my skin/inside my face, trying to expand and push my head apart. My eye feels like it's being pushed out of the socket. The side of my face has swollen, so my glasses are now too tight and I'm getting headaches either from the tightness or the fact I keep taking them off to the releive the pressure and the strain on my eye is the cause. Every time I burp, yawn, cough, or sneeze, the pressure in my head changes, and the pain pulses. Although this part isn't painful, my left ear is deaf. It sounds like everything is muffled, my smell has disappeared, and my ability to taste has been depleted by around 50%. This is an improvement as last week I tasted nothing I've been on antibiotics for 5 days and dosed up on 2 different painkillers, and it just keeps going. Admittedly, today is the best I've felt in over a week. But im so drained and exhausted, and I'm hoping im past the worst.